Not Applicable.
This invention relates to compositions of interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers blended with one or more conductive additives and, optionally one or more additional polymers.
The generic class of materials of xcex1-olefin/vinyl or vinylidene monomer substantially random interpolymers, (including interpolymers of xcex1-olefin/vinyl aromatic monomers) and their preparation, are known in the art, and are described in EP 416 815 A2.
The structure, thermal transitions and mechanical properties of substantially random interpolymers of ethylene and styrene containing up to about 50 mole percent styrene have been described (Y. W. Cheung, M. J. Guest; Proc. Antec ""96 pages 1634-1637). The interpolymers were found to have glass transitions in the range xe2x88x9220xc2x0 C. to +35xc2x0 C., and had no measurable crystallinity above about 25 mole percent styrene incorporation, i.e. they are essentially amorphous.
Materials such as substantially random ethylene/styrene interpolymers offer a wide range of material structures and properties which makes them useful for varied applications, such as asphalt modifiers or as compatibilizers for blends of polyethylene and polystyrene (as described in U.S. Pat. No. 5,460,818.) Although of utility in their own right, industry is constantly seeking to improve the applicability of these interpolymers. To perform well in certain applications, these interpolymers could be desirably improved, for example, in the areas of electrical conductivity and/or magnetic permeability.
The ability to impart either electrical conductivity or magnetic permeability to materials can be an important factor in a number of applications. For instance the property attribute of semiconductivity (about 10xe2x88x929 to 10xe2x88x922 S/cm) in a material enhances its use in applications which require electrostatic painting, electronics manufacturing and shipping, conductive fibers for antistatic carpet and clothing, antistatic flooring, and also for semiconductive films. Higher levels of conductivity are also required in applications such as cable shielding, resettable fuses, EMI shielding, and direct electroplating onto plastics. In general, the key issues for conductive modification of existing materials are the maintenance of acceptable properties in the host material and minimization of the amount of conductive additive required to add the conductivity which can also be an issue for cost.
Magnetic permeability is a desirable feature in applications such as electromagnetic wave attenuation, that is, shielding of electrical equipment and circuits in numerous electrical devices from the deleterious effects of electromagnetic interference (EMI) present in the environment. EMI shielding is also important in containing the EMI within the EMI generating source as dictated by the specifications for electrical equipment imposed by both Government and private industry.
We have now found that interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers become semielectrically conductive (about 10xe2x88x929 to 10xe2x88x922 S/cm) by melt or solution blending low loadings of a conductive additive such as conductive carbon. We have also found that such interpolymers become significantly conductive ( greater than 0.01 S/cm) when larger amounts of conductive additives are incorporated.
We have also found that the combination of relatively small amounts of interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers, a conductive additive, and an additional polymer can enhance the conductivity of the blend in comparison to the cases where there is no interpolymer, when all other factors such as conductive additive level and processing parameters are held constant.
We have also found that this enhancement can bring the conductivity to the surface of the composite under conditions which may otherwise yield an insulating surface.
Finally, we have found that the use of two or more interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers which have differing vinyl or vinylidene monomer contents can also significantly enhance the conductivity both at the surface and throughout the bulk of the composite.
In yet another aspect of the present invention, the interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers can be mixed with intrinsically conductive polymers (ICP) such as certain appropriately doped polyanilines, to produce a relatively optically transmissive films having antistatic properties when, for example, cast from solution. Certain appropriately doped polyanilines (as described for instance in copending Provisional US Application filed on Oct. 15, 1997 entitled xe2x80x9cElectrically-Conductive Polymersxe2x80x9d by Susan J. Babinec et al., and herein incorporated by reference) appear to be miscible with the interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers. These mixtures can produce a clear, rather than cloudy or opaque, film as a result of good miscibility such that discreet particles are not seen under a light microscope at magnifications as high as 500 X. Such effectively transparent films which are semiconductive and do not contain discreet particles are a much desired product, for example, for antistatic applications related to electronics manufacturing and shipping. The miscibility of certain polyanilines in the interpolymers of xcex1-olefin monomers with one or more vinyl or vinylidene aromatic monomers and/or one or more hindered aliphatic or cycloaliphatic vinyl or vinylidene monomers is also an important feature in processes such as blowing foams, and films where fine microstructure is also critical.
This invention relates to blends of polymeric materials comprising
(A) of from about 1 to about 99.99 weight percent based on the combined weights of Components A, B and C of at least one substantially random interpolymer; and wherein said interpolymer;
(1) contains of from about 0.5 to about 65 mole percent of polymer units derived from;
(a) at least one vinyl or vinylidene aromatic monomer, or
(b) at least one hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer, or
(c) a combination of at least one vinyl or vinylidene aromatic monomer and at least one hindered aliphatic or cycloaliphatic vinyl or vinylidene monomer;
(2) contains of from about 35 to about 99.5 mole percent of polymer units derived from at least one aliphatic xcex1-olefin having from 2 to 20 carbon atoms;
(3) has a molecular weight (Mn) greater than about 1,000;
(4) has a melt index (I2) of from about 0.01 to about 1,000;
(5) has a molecular weight distribution (Mw/Mn) of from about 1.5 to about 20;
and
(B) of from about 99 to about 0.01 weight percent based on the combined weights of Components A, B, and C of one or more conductive additives and/or one or more additives with high magnetic permeability ; and
(C) of from 0 to about 98.99 weight percent based on the combined weights of Components A, B, and C of one or more polymers other than A.